Calcium ions potentiate lipoxygenase activity of cytochrome c at the physiological pH.
Cytochrome c oxidized linoleic acid, with lipoxygenase-like activity, to 9-hydroperoxy-10,12-octadecadienoic acid (9-HpODE), 13-hydroperoxy-9,11-octadecadienoic acid (13-HpODE), 13-keto-9,11-octadecadienoic acid (13-KODE), and hydroxy-epoxy-octadecenoic acids (HEPOs) in the presence of calcium chloride at the physiological pH of 7.5. In the absence of calcium, the reaction was remarkably reduced. Statistically significant increase of 13-KODE was observed 1 min after the reaction was started by adding calcium. Calcium chloride at concentrations as low as 30 microM caused statistically significant increase of 13-KODE production in the presence of 1 microM cytochrome c, and cytochrome c at concentrations as low as 10 nM caused statistically significant increase of 13-KODE production in the presence of 2 mM calcium. The addition of bleomycin enhanced the reaction, and the addition of adriamycin attenuated the reaction. The same oxidized linoleic acid products were found in the submitochondrial particles which were hydrolyzed by phospholipase-A2 in the presence of calcium. Lipoxygenase activity potentiated by calcium may be involved in the lipid peroxidation in the submitochondrial particles hydrolyzed by phospholipase-A2.
Iwase
H
H
Department of Forensic Medicine, Faculty of Medicine, University of Tokyo, Japan.
Sakurada
K
K
Takatori
T
T
Nagao
M
M
Niijima
H
H
Matsuda
Y
Y
Kobayashi
M
M
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D003574:Cytochrome c Group / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D019787:Linoleic Acid / Q000378:metabolism; D008042:Linolenic Acids / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008084:Lipoxygenase / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000201:enzymology / Q000502:physiology; D010545:Peroxides / Q000378:metabolism / Q000494:pharmacology; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D013229:Stearic Acids / Q000737:chemistry / Q000378:metabolism
D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D008042:Linolenic Acids; D010545:Peroxides; D013229:Stearic Acids; C064441:13-oxo-9,11-octadecadienoic acid; D019787:Linoleic Acid; D008084:Lipoxygenase; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium